This invention relates to continuous molding of synthetic resin to produce features that are integral with a base sheet, and has particular application to the production of fastener elements for touch fasteners and the like.
Hook elements for hook-and-loop touch fasteners and other products are effectively produced by the machine and method of Fischer U.S. Pat. No. 4,794,028. In commercial production, a mold roll is formed by a large number of thin, disk-shaped mold rings and spacer rings which are stacked concentrically about a central barrel. At the periphery of the mold rings are cavities for molding the hook elements. In current production machines each cavity of a mold ring has been formed, one at a time, by wire electro-discharge machining (EDM).
In practice of the Fischer method, molten resin is forced into the mold cavities, tending to raise the temperature of the mold rings. A fluid coolant is circulated through cooling passages within the barrel on which the rings are mounted to remove the heat from the rings. In this way an appropriate temperature of the mold cavities is maintained so that the product becomes sufficiently solid that it can be withdrawn on a continuous basis, typically without opening the mold cavities.
The Fischer technique has proven successful commercially and has represented an important advance over prior proposals in this field such as Menzin et al. U.S. Pat. No. 3,752,619.